8th Grade-Ch. 4 Sec. 3 Lives of Stars


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8th Grade-Ch. 4 Sec. 3 Lives of Stars

  1. 1. Sec. 3 Lives of Stars
  2. 2. lifetimes of stars <ul><li>how long a star lives depends on its mass </li></ul><ul><li>greater the mass- shorter the lifetime </li></ul>
  3. 3. star’s life cycle
  4. 4. <ul><li>nebula = large cloud of gas & dust </li></ul><ul><li>birthplace of stars </li></ul><ul><li> </li></ul>
  5. 5. Image by NASA/STSCI/Nolan Walborn/Hubble Heritage Team nebula
  6. 7. 1. protostar <ul><li>Earliest stage in star’s life </li></ul><ul><li>Contracting cloud of gas & dust w/ enough mass to make star </li></ul>
  7. 9. sun 2. main sequence star (developed star)
  8. 10. 3. red giant or supergiant start to run out of fuel- outer layers expand
  9. 12. <ul><li>When star runs out of fuel, becomes : </li></ul><ul><li>white dwarf or </li></ul><ul><li>neutron star or </li></ul><ul><li>black hole </li></ul>depends on star ’s mass
  10. 13. small & medium stars become <ul><li>white dwarf- </li></ul><ul><ul><ul><ul><ul><li>cooled blue-white core left behind </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>about size of Earth </li></ul></ul></ul></ul></ul><ul><li> same mass as Sun </li></ul>
  11. 14. This Hubble Space Telescope image shows Sirius A, the brightest star in our nighttime sky, along with its faint, tiny stellar companion, Sirius B. Astronomers overexposed the image of Sirius A [at center] so that the dim Sirius B [tiny dot at lower left] could be seen.
  12. 15. <ul><li>5. black dwarf- </li></ul><ul><li>when white dwarf stops glowing </li></ul>
  13. 16. <ul><li>giant & supergiant stars </li></ul>4. supernova - explosion of a dying giant or supergiant star <ul><li>one of the most dazzling events in the universe </li></ul>
  14. 17. supernova
  15. 18. <ul><li>5. neutron star- small, dense star </li></ul><ul><ul><ul><ul><ul><li>- 3 X mass of Sun </li></ul></ul></ul></ul></ul>
  16. 19. pulsar <ul><li>Spinning neutron star </li></ul><ul><li>Emits pulses of radio waves </li></ul>
  17. 21. <ul><li>5. black hole- most massive stars </li></ul><ul><ul><ul><ul><li>form from stars that have 40 times the mass of sun </li></ul></ul></ul></ul><ul><ul><ul><ul><li>gravity is so strong that nothing can escape- not even light </li></ul></ul></ul></ul><ul><ul><ul><ul><li>x-rays detect them </li></ul></ul></ul></ul>
  18. 22. The remains of the most massive stars collapse into black holes. This artist’s impression shows a black hole pulling matter from a companion star.
  19. 23. Not even light can escape from a black hole.
  20. 24. ( unsequenced human life cycle page ) nebula protostar developed star supergiant supernova black hole
  21. 25. nebula protostar protostar protostar
  22. 26. Life Cycle of a Star nebula = huge cloud of gas & dust protostar = beginning of star red giant or supergiant = star expands, outer layers cool supernova = enormous explosion of a giant star white dwarf = dim star that forms from a red giant black dwarf = runs out of fuel dead star black hole = core collapses to a tiny point with a very strong gravitational pull neutron star = dense remains of a massive star’s core low mass star high mass star very high mass massive star developed star (main sequence star)